The present invention relates to a mechanical pencil in which an inner mechanism is movable between a writing position and a retracted position by rotation of the axial pencil body, wherein in the writing position, a lead is supplied from a front end of the pencil by depression of a rear end member thereof.
There have heretofore been provided a so-called "double-push" type mechanical pencil in which an inner mechanism is movable between a writing position and a retracted position by a long stroke depression of the axial pencil body and at the writing position a lead is supplied from the front end of the pencil by a short stroke depression. The double-push type mechanical pencil is very convenient since the sharp front end of the mechanical pencil is retracted into the mechanical pencil to thereby prevent the user's pocket from being torn the user inadvertently being stabbed with the sharp front end. However, such a mechanical pencil has the following disadvantages.
A rather strong spring is needed for moving the inner mechanism. Also, to advance the mechanism, a long stroke is needed against a force of a chuck spring used for clamping the lead in addition to the force of the above-described strong spring. Therefore, the operator must use a rather strong force.
In order to remedy this defect, the force of the spring applied to the inner mechanism movement can be reduced. However, in this case it is difficult to distinguish a strong long stroke push from a weak short push. Such a mechanical pencil is inconvenient since the inner mechanism can readily be erroneously retracted into the mechanical pencil body.
In another aspect of such a prior art mechanical pencil, a cam mechanism is frequently used for moving the inner mechanism. A cam sleeve constituting a part of the cam mechanism must have a rather large diameter so that the diameter of the outer pencil body is increased. This is not desirable in view of aesthetic considerations. Furthermore, in the prior art mechanical pencil, a push rod must be long enough to advance the inner mechanism by a long stroke and further to supply a lead by a short stroke. In addition, in the long stroke operation, an idle distance for operating the cam mechanism is needed. For these reasons, the required stroke length is longer than desirable. This leads to an increase of the push rod length. Due to this, the prior art mechanical pencil is also inferior in aesthetic design.
An object of the present invention is thus to provide a novel mechanical pencil, overcoming the above noted defects, and specifically to provide an easy to use mechanical pencil having a superior aesthetic design.